The past decade has witnessed widespread adoption of personal wireless communication devices, including handheld cellular telephones, dedicated text messaging devices, and hybrid devices that combine communication and other functions. Wireless communication devices include antennas that are used to transmit and receive information-bearing RF and/or microwave signals. Antennas can be characterized by the efficiency with which they radiate and receive signals and by their gain patterns, which characterize how well the antenna can transmit and receive signals in each direction.
Handheld wireless communication devices differ from larger radio communication equipment in that they are typically operated in close proximity to a person's body, e.g., held at the side of a person's face. From an electromagnetic view point, the human body is an irregularly shaped object in which the complex permittivity (conductivity and permittivity) is spatially distributed. Although considered in isolation, an antenna of a wireless communication device can be analyzed and understood using a variety of mathematical methods, placing the antenna near a person's body complicates matters and can dramatically change the performance of the antenna from what is predicated based on mathematical models of the antenna in isolation. Interaction with a person's body may lead to loss of signal energy, and alteration of the gain pattern.
In order to better understand the effect of a user's body on antenna performance, models of the human head that are suitable for electromagnetic testing have been made. These models typically take the form of a hollow molded model of a head that is filled with an electrolyte solution that is intended to simulate the bulk electromagnetic properties of a person's head. Models of a human hand have also been constructed from carbon-and-aluminum loaded silicone rubber, as well as semi-flexible shell filled with an electrolyte solution that is intended to simulate the bulk electromagnetic properties of a person's hand.
Existing model hands are overly complicated, thus introducing undesirable by products. For example, when using the fully articulated hand phantom, the precise placement of the lesser three digits (middle, ring and pinky) on the surface of the wireless communication device under test is difficult to determine, and can be difficult to achieve in practice for the fully articulated hand phantom. Also, the precise contact location of the thumb on the wireless communication device varies. Typically, the end of the thumb is near the top of the device, and the thumb end at the top plane of the phone is preferred. The position and contact location of the “pointer” digit is the most contentious. It is desirable for the pointer digit to be extended and contact the wireless communication device somewhere above the center line of the device and roughly in the middle of the device left to right.
Thus, parameters for model hands of hand phantoms that are truly required need to be distinguished from parameters that are merely desirable but not required. Based on this information, it is desirable to have a simplified universal model of a hand phantom having minimum requirements for the hand model by including the parameters that are truly required.